I am sensitive to criticism, but I tend to only feel defensive or upset if it seems unfair to me. If it's legit criticism, then I may feel a bit mad at myself, but ultimately I will consider it and use it to improve.
It depends on many factors...
What appears to be the motivation of the other person for criticizing me or my work? Many times, people do not have good motives, or they are just reacting on emotion themselves.
Is the criticism valid? Sometimes people are just plain wrong; they have grossly misinterpreted something, they are the one being too sensitive or too demanding, or they simply have no idea of what they are talking about. People seem to think "my opinion = fact" too often also, and they jump the gun on criticizing, but instead of offering anything useful, they are just insulting because they have no legitimate reason to back up their criticism. For instance, just because you do not LIKE something, does not mean it is BAD. People also have short term views in determining what works and what does not.
Is the criticism given in a fair and helpful way? Even if someone deserves criticism, they do not deserve to be beaten down. I think the criticizer has the responsibility to deliver their criticism effectively, and if they fail to do so, then they cannot really expect someone to listen to them. You can't say "I don't like this" and expect someone to read your mind and find out what you do like and fix it.... If you cannot communicate clearly, then maybe it's your own fault that the other person is not delivering what you want/need.
Lastly, it IS PERSONAL and if the person claims it is not then I look back to #1, at their motivations. If you are a person, then a comment made specifically towards you and about you is personal. If you are a person, then the criticism you are giving is your personal opinion. People claiming that criticism is not personal often do so as an excuse to flout basic ethics and manners so as to get away with less than decent behavior. If people stopped objectifying others as "employees" or "students" and remembered they are individual human beings, then maybe everyone would deal with one another more compassionately. Personalizing interactions produces better results all around because it reminds people they are dealing with another human and not some machine made to serve them.
EDIT: Oh yeah, I also find most people very quick to criticize and slow to praise. This is a mistake. I think many people respond better to praise & will grow more from it than criticism (although criticism is necessary at times). You reinforce higher expectations in a positive way by showing they are reachable and you create a feeling of wanting to keep the respect they've earned. Constant criticism can make people only live up to the bare minimum necessary to avoid it and creates motivation from fear which doesn't promote growth because it stifles creativity and self-esteem.